of the Fishery Board for Scotland. 250 
branches of the fourth pair are stouter than those of the outer branches 
of the same pair in that species. The terminal spines are also slightly 
different (figs. 5,6). The fifth pair appears to be wanting in the female. 
The abdomen is, proportionally, scarcely so long as that of Scolecithrix 
hibernica. The first segment is about equal to the combined length of 
the next two, and is rather more dilated ; the second segment is some- 
what shorter than the third ; but the length of the third and fourth is 
about equal. The caudal furce, which are about as long as broad, are 
somewhat longer than the segment to which they are articulated, and the 
furcal setz are long and plumose (fig. 8), 
Description of the Male.—The male of Scolecithrix pygmea resembles 
that of Scolecithrix hibernica in several aspects, but differs particularly 
in the structure of the fifth pair of thoracic feet.. In this pair the basal 
joint is stout, and armed with several curved spines as in Scolecithrix 
hibernica, but the right branch is more slender, and the first joint of 
that branch is not so irregular in outline. In the present species the 
first joint of the right branch becomes gradually but only slightly 
dilated towards the distal end, and is not produced into a large lobe as in 
Scolecithrix hibernica; the second joint is smaller, and proportionally 
much more slender than in that species ; the marginal thumb-lke process 
is small, and situated near the middle of the joint. The left branch of 
the present form (fig. 7 1.) is also rather more slender than that of 
Scolecithrix hibernica, but the process at the distal end of the second 
joint is somewhat more produced and attenuated. The abdomen consists 
of five segments. The second, which is rather longer than the first, is 
about one and a half times the length of the following segment; the 
third and fourth segments are sub-equal, but the last is very small; the 
furce are about equal in length to the penultimate segments of the 
abdomen (fig. 9). Figure 10 represents the fifth thoracic feet of the 
male of Scolecithrix hibernica for comparison with those of the species’ 
now described. The figures of both are of the same maguification. 
Habitat.—Firth of Clyde and Loch Fyne. Not very rare. 
Remarks.—This Scolecithriv has been under observation for a con- 
siderable time, At first I was inclined to regard it simply as a form of 
Scolecithrix hibernica, but as it continues to turn up both alone and in 
company with that species, and as all of the specimens are characterised 
by the same distinctive features, I think it will be more satisfactory to 
describe it under a separate name. It is distinctly a smaller species than 
Scolecithrix hibernica, being scarcely a millemetre in length. If male 
and female specimens of the two species be placed side by side—the males 
together and the females together—the difference in size is readily 
noticed. The structure of the fifth thoracic feet of the male, and the 
structure and armature of the anterior foot-jaws of the female, are 
characters by which the species may be distinguished ; the lengths of the 
abdominal segments in both male and female are also proportionally 
different. 
Centropages typtcus, Kroyer. 
1849. Centropages typicus, Kroyer. Nat. Tidskr., (2) iL, 
p. 588, t. 6. 
This species appears to be much rarer in the Clyde than Centropages 
hamatus, for while the latter form occurs in nearly all gatherings 
collected in August and September last year, I have only three records 
for Centropages typicus. On the East Coast of Scotland Centropages 
typicus appears to be more common. In a series of gatherings from the 
